#22-11: determine the difference in area between circle a and circle b. use 3.14 for pi.

7.065

Step-by-step explanation:

There are two ways to do this:

(Note: area = pi * r^2)

Method 1:

Diameter of A = 4, so radius = 4/2 = 2

Area of A = 3.14 * 2^2 = 12.56

Diameter of B = 5, so radius = 5/2 = 2.5

Area of B = 3.14 * 2.5^2 = 19.625

Difference in area = 19.625 - 12.56 = 7.065

Method 2:

First find out how much larger the diameter of B is than A, so 5/4 = 1.25.

What this means is if you take the diameter of A and multiply it by 1.25, you get the diameter of B.

When dealing with area, the area of B will be 1.25^2 times bigger than A.

Area of A = 3.14 * 2^2 = 12.56

So area B = 12.56 * 1.25^2 = 19.625

Difference = 19.625 - 12.56 = 7.065